Holders Australia stunned by Jordan in their opening 2019 AFC Asian Cup game

Australia made the worst possible start to the defence of their Asian Cup crown on Sunday as Graham Arnold's Socceroos were handed a 1-0 defeat by unfancied Jordan.

The Australians, who won the title on home soil four years ago, dominated for long spells but were unable to find a way to cancel out Anas Bani Yaseen's 26th minute header in the Group B clash at Hazza bin Zayed Stadium.

"It was one of those days," Arnold said.

"A frustrating day and the ball didn't seem to bounce. But you've got to give full credit to Jordan and they've shown that they had a lot of fight."

Vital Borkelmans' Jordan were resolute in defence against an Australia side that struggled to turn their domination into chances. The Socceroos went into half time trailing by a goal and were fortunate not to be further behind.

Bani Yaseen put his side in front when he was given the time and space to head Baha Abdelrahman's corner home unchallenged, powering the ball beyond the flat-footed Mat Ryan.

Australia were beaten by Anas Bani-Yaseen's 26th-minute header. Getty

Four minutes later Abdelrahman almost added a second when his free kick from the edge of the area speared towards goal, only for Ryan to push the ball on to the woodwork before it was cleared.

For all their possession in the opposition half, Australia crafted few clear-cut opportunities, with Awer Mabil's shot coming back of goalkeeper Amer Shafi's legs and Jamie MacLaren heading high over the bar.

Mabil hit the woodwork late in the second half as Australia grew increasingly desperate to find an equaliser and Shafi was kept busy until the final kick of the game but Jordan held on for a famous win.

Australia next face Palestine on Jan. 11 while Jordan will take on Syria.